The invention concerns an electric driven tool device, in particular, a manual electric tool device, comprising an asynchronous electromotor or a brush-less synchronous electromotor, and a computer-controlled motor control means, i.e. with an, in particular, microprocessor-controlled control electronics.
Manual electric driven tool devices are mainly driven by electromotors having a current converter or commutator with carbon brushes. In particular, so-called universal motors are used. Carbon brushes are subject to constant wear and must be replaced after some time. Commutator motors of this type have almost linear performance characteristics up to a certain load. At higher loads, the motor rotational speed decreases and the motor current increases. There are also manual electric tool devices having a controlled commutator motor. The motor rotational speed is thereby kept constant with increasing load mostly via phase section control, such as e.g. in the electric tool device distributed by the applicant under the trade name “Vario-Constamatik”. If the load of the motor exceeds a certain value, control via the control electronics is not possible, inevitably producing uncontrolled motor characteristics.
In so-called semi-stationary electric tool devices, such as e.g. circular saw benches, reciprocating table type planers, strip straightening machines etc. an asynchronous electromotor or a synchronous electromotor are conventionally used which are operated at the constant frequency of the motor drive voltage. The frequency used is, in particular, the mains frequency, in Europe 50 Hertz and in the U.S.A. 60 Hertz. DE 298 09 768 U1 discloses a semi-stationary electric tool device in the form of a circular saw bench, comprising an asynchronous electromotor or a synchronous electromotor, which is operated at a higher, constant frequency of 300 to 400 Hertz compared to the mains frequency by using a frequency converter. The rotational speed of the motor is therefore correspondingly higher and a downstream reducing gear is disposed in the drive motor.
DE 198 16 684 A1 discloses a manual electric tool device comprising an electromotor without carbon brushes. The device unit contains the drive motor and the electric components of the electromotor control, which are directly required for control thereof and has a separate external current supply unit.
It is the underlying purpose of the invention to produce an electric tool device which has linear performance characteristics similar to those of a commutator motor comprising carbon brushes but without the need for a commutator carbon brush system, which is susceptible to wear. The motor control device should function without expensive sensors, such as e.g. tachometer sensors or Hall sensors.